Abstract

A radio frequency oscillator circuit based on a proximity detector integrated circuit is described as an alternative for the traditional tunnel diodeoscillator used for pulsed magnetic field measurements at low temperatures. The proximity detector circuit design, although less sensitive than tunnel diodeoscillator circuits, has a number of essential advantages for measurements in the extreme environments of pulsed magnetic fields. These include the insensitivity of operation to voltages induced in the inductorcoil, the elimination of a diode bias circuit and tuning, and a broad dynamic range of resonant frequency variation. The circuit has been successfully applied to measure the superconducting upper critical field in single crystals up to 60 T.

Received 04 February 2009Accepted 14 May 2009Published online 30 June 2009

Acknowledgments:

Work at Los Alamos National Laboratory (LANL) was supported by NSF-DMR-0654118, DOE, and the State of Florida. M. M. Altarawneh is supported in part by NSF-DMR 0602859 (FSU) and LANL LDRD-DR20070013. LANL is operated by LANS LLC. We thank N. Ni, S. L. Bud’ko, and P. C. Canfield for providing the sample.